Automatic conveyor systems are used to convey or route articles between work stations or other locations, and in many conveyor systems it is desirable to move the articles from one vertical level to another.
U.S. Pat. No. 4,465,177 describes an elevator for a conveyor system which consists of a pair of endless chains mounted to travel in parallel offset vertical paths of travel. The opposite corners of a plurality of carriers or platforms are connected to the respective chains by bearing assemblies, and as the chains move in synchronization in their respective paths of travel, the carriers will move in a generally rectangular path consisting of an upward vertical run, an upper horizontal run, a downward vertical run, and a lower horizontal run. With this construction, the carriers will remain in a horizontal attitude at all times in their path of travel.
In the conventional elevators, as used in the past, the carriers are connected to both chain drives, and therefore it is necessary that the chain drives be precisely aligned. However, it is a difficult and costly procedure to precisely align the chain drives. If there is not precise alignment between the drive shafts and sprockets of the two chain drives, the chain links, as well as the pins which connect the bearing assemblies to the chain links, can be subjected to excessive stress.